Plug gauges



Sept. 15, 1959 C. H. PORTER PLUG GAUGES Filed Sept. 5, 1957 //v ray wci/FKL 5.3 1, 17 60000 25 s l t I I I r United States Patent PLUG GAUGESCharles Hackwood Porter, Birmingham, England Application September 5,1957, Serial No. 682,221

Claims priority, application Great Britain September 11, 1956 1 Claim.(Cl. 33-178) This invention relates to plug gauges of the bar plug typefor use in the inspection of hollow cylindrical work pieces, in whichbar plugs are arranged perpendicularly at the ends of an intermediatebody or handle, said plugs having precision ground part-spherical endsserving as go" and no go gauges for hollow cylindrical work pieces whosecurvature is substantially similar to that of the said ends.

Presently, these plugs are fixtures with the body or handle and,consequently, each gauging end possesses between its part-spherical endsonly one line contact for use in gauging hollow cylindrical work pieceswhose bore is of substantially similar curvature to that of the saidends of the gauge. The result is that as inspection control proceeds,inevitable wear occurs on the spherical ends, and gauges cannot berelied upon for attaining the high standard of accuracy demanded by theinspection control.

The primary object of the present invention is to avoid or substantiallyreduce this drawback in a simple and inexpensive manner and therebyprolong the useful life of such gauges.

According to the present invention in a bar plug gauge of the typereferred to, the bar plugs are arranged to be held so as to be capableof being turned about their axes so that ditferent line contacts can beprovided between the spherical ends..

Preferably each bar plug is provided between its ends with a cylindricalneck which is turnably held in jaws at the end of the body or handle.

The body or handle may be made of two similar parts which are releasablysecured together so as to hold the bar plugs by their necks between jawsformed by complementary recesses in the body or handle parts.

In order that the invention may be fully understood and more readilycarried into practice, a constructional example thereof will behereinafter described with reference to the accompanying drawings, inwhich Figure 1 is a perspective view of a bar plug gauge according tothe invention,

Figure 2 is a side view of the gauge shown in Figure 1,

Figure 3 is an end view of Figure 2,

Figure 4 is a plan view of Figure 2, and

Figure 5 is an end view in medial section of Figure 2.

Referring to the drawings, in the construction shown therein, the barplug gauge 1 comprises a body or handle 2 and bar plugs 3 and 4respectively, mounted at either end of the handle 2, which consists oftwo similar parts 5 and 6, conveniently moulded from a thermosettingmaterial. The parts 5 and 6 each have part-cylindrical recesses 7 attheir ends, opposed recesses cooperating to form jaws 8 which serve toclamp the bar plugs 3 and 4 in given axial positions. Each bar plug 3, 4has portions 9, 10 respectively provided with longitudinal serrationsadapted to cooperate with the jaws 8 and hold the bar plugs 3, 4 intheir adjusted positions. The parts 5, 6 of the handle 2 are securedtogether in two positions adjacent the jaws 8 by screws 11 and nuts 12.

Each plug 3, 4- has part-spherical ends 13, 14 respectively, which areemployed to gauge the bore of hollow cylindrical work pieces, such borebeing substantially similar in curvature to that of the part-sphericalends 13, 14. After the gauge has been in use for some time with constantline contact between the bar plug ends and the bores of the work piecesgauged, wear along such line takes place. A fresh line contact can beobtained by unscrewing the screws 11 so as to loosen the jaws 8 andenable the bar plugs 3 and 4 to be turned about their axes, the screws11 being tightened to clamp the bar plugs 3 and 4 in their newpositions. Adjustment when required can be repeated until all unwornline contacts have been used, when the bar plugs can be replaced by newones. By this expedient the gauge is provided with a very much longerlife compared with hitherto, when replacement was necessary after thewearing of one line contact only.

For convenience, each handle part 5 and 6 is also provided with recesses15 on its outer surface adjacent each jaw-part recess 7.. Opposed pairsof the recesses 15 form finger grips for using the gauge and for quicklyidentifying the go and no go bar plugs, and for this purpose can bediiferently coloured, for example, green for the go end of the gauge andred for the no go end.

What is claimed is:

For gauging hollow cylindrical work pieces, a bar plug gauge comprisingan elongated handle assembly of two similar handle parts, screw and nutmeans for releasably securing said handle parts together, jaws at eitherend of the handle assembly and formed by opposed cooperating lateralcylindrical recesses in said handle parts, a bar plug of fixed lengthclamped in each of said jaws when said handle parts are secured togetherand axially rotatable in said jaws when the handle parts are released, aserrated portionon each bar plug in registration with said jaws, andpart-spherical ends on said bar plugs whose curvature corresponds tothat of the bore of the work pieces intended to be gauged, said barplugs presenting a different line contact upon axial rotation thereof.

References Cited in the file of this patent UNITED STATES PATENTS799,912 Masterson Sept. 19, 1905 1,657,326 Steinle Jan. 24, 19282,089,124 Kleinmann Aug. 3, 1937 2,322,033 Le Brun June 15, 19432,679,694 Cybulski June 1, 1954 FOREIGN PATENTS 582,291 Great BritainNov. 12, 1946 616,542 Great Britain Jan. 24, 1949

